Slider with leading edge blend and conformal step features

ABSTRACT

A method of forming a slider includes forming a leading edge blend on a leading edge of the slider. After the leading edge blend is formed, the method further includes forming at least one step feature conformal to the leading edge blend. A slider having an air bearing surface includes a leading edge blend and at least one step feature conformal to the leading edge blend.

BACKGROUND

Information storage devices are used to retrieve and/or store data incomputers and other consumer electronics devices. A magnetic hard diskdrive is an example of an information storage device that includes oneor more heads that can both read and write, but other informationstorage devices also include heads—sometimes including heads that cannotwrite.

The typical hard disk drive includes a head disk assembly (HDA) and aprinted circuit board (PCB) attached to a disk drive base of the HDA.Referring now to FIG. 1, the head disk assembly 100 includes at leastone disk 102 (such as a magnetic disk, magneto-optical disk, or opticaldisk), a spindle motor 104 for rotating the disk, and a head stackassembly (HSA) 106. The spindle motor typically includes a rotating hubon which disks are mounted and clamped, a magnet attached to the hub,and a stator. Various coils of the stator are selectively energized toform an electromagnetic field that pulls/pushes on the magnet, therebyrotating the hub. Rotation of the spindle motor hub results in rotationof the mounted disks. The printed circuit board assembly includeselectronics and firmware for controlling the rotation of the spindlemotor and for controlling the position of the HSA, and for providing adata transfer channel between the disk drive and its host. The headstack assembly 106 typically includes an actuator, at least one headgimbal assembly (HGA) 108 that includes a head, and a flex cableassembly 110.

During operation of the disk drive, the actuator must rotate to positionthe heads adjacent desired information tracks on the disk. The actuatorincludes a pivot bearing cartridge 112 to facilitate such rotationalpositioning. One or more actuator arms extend from the actuator body. Anactuator coil 114 is supported by the actuator body opposite theactuator arms. The actuator coil is configured to interact with one ormore fixed magnets in the HDA, typically a pair, to form a voice coilmotor. The printed circuit board assembly provides and controls anelectrical current that passes through the actuator coil and results ina torque being applied to the actuator. A crash stop is typicallyprovided to limit rotation of the actuator in a given direction, and alatch is typically provided to prevent rotation of the actuator when thedisk drive is not in use.

In a magnetic hard disk drive, the head typically comprises a bodycalled a “slider” that carries a magnetic transducer on its trailingend. The magnetic transducer typically comprises a writer and a readelement. The magnetic transducer's writer may be of a longitudinal orperpendicular design, and the read element of the magnetic transducermay be inductive or magnetoresistive. During operation of the magnetichard disk drive 100, the transducer is typically supported in very closeproximity to the magnetic disk 102 by a hydrodynamic air bearing. As themotor 104 rotates the magnetic disk 102, the hydrodynamic air bearing isformed between an air bearing surface of the slider of the head, and asurface of the magnetic disk 102. When the disk drive 100 is powereddown, the HSA 106 rotates clockwise until a load tab of HGA 108 contactsa ramp 116 thereby lifting the slider from the surface of disk 102before the disk 102 stops rotating. The thickness of the air bearing atthe location of the transducer is commonly referred to as “flyingheight.”

Magnetic hard disk drives are not the only type of information storagedevices that have utilized air bearing sliders. For example, air bearingsliders have also been used in optical information storage devices toposition a mirror and an objective lens for focusing laser light on thesurface of disk media that is not necessarily magnetic.

The flying height is a key parameter that affects the performance of aninformation storage device. Accordingly, the nominal flying height istypically chosen as a careful compromise between each extreme in aclassic engineering “trade-off.” If the flying height is too high, theability of the transducer to write and/or read information to/from thedisk surface is degraded. Therefore, reductions in flying height canfacilitate desirable increases in the areal density of data stored on adisk surface. However, the air bearing between the slider and the disksurface cannot be eliminated entirely because the air bearing serves toreduce friction and wear (between the slider and the disk surface) to anacceptable level. Excessive reduction in the nominal flying heightdegrades the tribological performance of the disk drive to the pointwhere the disk drive's lifetime and reliability become unacceptable.Moreover, if the slider roll angle becomes excessive, then the airbearing may become even thinner at a corner of the slider than at thelocation of the transducer, potentially further degrading tribologicalperformance.

Edge blending, referring to abrading an edge of the slider to produce acurved surface, was used for some time on sliders for improving flyingperformance where the curved edge provided better flyingcharacteristics. However, as performance requirements for the flyingheight became increasingly critical, the controllability of the edgeblending process was insufficiently precise, particularly as compared toother methods of shaping the air bearing surface of the slider.Furthermore, the blending removed the carbon overcoat from the slider inthe area that was being abraded. These drawbacks caused edge blending tofall into disuse.

SUMMARY

A method of forming a slider includes forming a leading edge blend on aleading edge of the slider. After the leading edge blend is formed, themethod further includes forming at least one step feature conformal tothe leading edge blend. A slider having an air bearing surface includesa leading edge blend and at least one step feature conformal to theleading edge blend.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a disk drive usable with a slider according tovarious embodiments of the particular invention;

FIG. 2 illustrates a profile of a slider according to a particularembodiment of the invention;

FIG. 3 illustrates a leading edge blend according to a particularembodiment of the invention; and

FIG. 4 illustrates a method according to an embodiment of the presentinvention for forming a slider with a leading edge blend.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 illustrates a head 200 comprising a slider 202 that includes atransducer 204 for reading information from a magnetic disk medium. Incertain embodiments, the transducer 204 is a merged thin film magnetictransducer comprising an inductive writer and magnetoresistive readelement. In such embodiments, the magnetoresistive element may be agiant magnetoresistive element (GMR) or a tunneling magnetoresistiveelement (TMR). In such embodiments, the writer may be a perpendicularmagnetic recording (PMR) writer.

The slider 202, which is typically fabricated from a ceramic materialsuch as alumina titanium carbide (AlTiC). The slider 202 includes an airbearing surface 206, which may be formed on the surface of slider 202 byetching or ion milling and has a geometry that may be defined by use ofa mask. The slider 202 includes a trailing face 208 and a leading face210, and the slider 202 may be covered by an overcoat (not shown), whichis typically formed from diamond-like carbon (DLC), to protect theslider 202 and the transducer 204 from particles and objects that candamage the slider 202. The part of the air bearing surface 206 thatwould be closest to the disk when the slider 202 is flying over a diskdefines a datum or reference plane for the air bearing surface 206,herein referred to as the “primary plane” of the slider 202. Inpractice, the portions of the air bearing surface 206 that would beclosest to the disk (herein referred to as “highest” for ease ofreference) when the slider 202 is flying over a disk may not beperfectly coplanar with one another. For example, along a length of theslider from the trailing face 208 to the leading face 210, the airbearing surface 206 may bow outward in the media-facing direction. Thedegree of bowing in the slider 202 is referred to as the “crown” of theslider. The crown may be expressed, for example, in terms of thedifference between the highest points of the air bearing surface 206along the length of the slider 202, and it may also be expressed as adegree of change in such height per unit length of the slider 202.

In describing the slider 202, the terms “leading” (or “forward”) and“trailing” (or “aft”) are directions corresponding to the respectiveorientation of the ends of the slider 202 as the slider 202 would fly onthe air bearing over the magnetic disk medium. Thus, as the magneticdisk rotates under the slider 202, the leading end of the slider 202would fly over a particular point on the magnetic disk before thetrailing end. Similarly, the term “upstream” is used herein only todefine a directional convention to facilitate description of relativepositions on the air bearing surface 206, and does not require thepresence or existence of any stream. For example, “upstream” can beunderstood to refer to a range of directions across the air bearingsurface 206 that generally point away from the trailing face 208 andtowards the leading face 210, with “downstream” being the antonym of“upstream” in this sense. As such, in disk drive applications, upstreamdirections would ultimately be generally opposite the motion of anadjacent rotating disk surface. The “sides” of the slider 202 extendbetween the trailing face 208 and leading face 210. Structures on theslider 202 may be described as “inner diameter (ID)-side” or “outerdiameter (OD)-side” when the structure being described is nearer to theside of the slider that would be closest or farthest (respectively) fromthe center of the disk when the slider 202 is positioned over the disk.

In the illustrated embodiment, the slider 202 includes a leading edgeblend 212, shown in greater detail in FIG. 3. “Leading edge blend” inthis context refers to a curved surface formed at the intersection ofthe air bearing surface 206 and the leading face 210 by abrading orpolishing the slider 202. The shape of the leading edge blend 212 can begenerally characterized in terms of a blend penetration 214 and a blenddepth 216. The blend penetration 214 indicates the distance between theplane of the leading face 210 to the point at which the air bearingsurface 206 straightens, while the blend depth 216 indicates thedistance from the primary plane of the air bearing surface 206 to thepoint at which the leading face 210 straightens. In particularembodiments, the blend depth may be around 0.4 microns with a blendpenetration of around 2.5 microns. The slider 202 also includes aconformal step feature 218. The conformal step feature 218 is recessedfrom the primary plane of the air bearing surface 206, and it isconformal to the curvature of the leading edge blend 212. Such aconformal step feature 218 may be formed, for example, by blending theleading edge first and then etching or ion milling to recess aparticular portion of the curved surface. Conformal step features 218may include, for example, leading edge steps. In FIG. 3, the conformalstep feature 218 is a recessed step surface on the OD side of a highersurface chosen for ease of illustration, but it should be understoodthan any manner of step surfaces, channels, dams, or the like with anycombination of depths could also be used.

As contrasted with previous edge blending methods, the conformal stepfeatures 218 of various embodiments of the present invention areadvantageous in that the shape of the conformal step features 218 can becontrolled with relatively precise etching or milling techniques. Thus,the controllability of the edge blending process need not limit theprecision in forming particular features of the air bearing surface 206.This allows the flight of the slider 202 on the air bearing to bewell-controlled, but it also allows advantages of a blended leading edgesurface to be incorporated in the slider 202 as well. For example, theslider 202 may be able to regain its air bearing more easily whensubject to a mechanical disturbance, such as operational shock, thatdisrupts the flight of the slider 202. Likewise, if the slider 202collides with an object, the leading edge blend 212 may help to reducethe damage to the disk. Additionally, the trailing face 208 and thesides of the slider 202 may also include a blend, which may reduceparticle shedding from the slider.

FIG. 4 is a flow chart 300 illustrating an example method of forming aslider according to a particular embodiment of the present invention.The slider 202 is divided from a slider bar at step 302. The slider 202is lapped to define various surfaces at step 304. The lapping step 304may involve several difference lapping steps and process, such aslapping different sides, “rough” lapping to generally define a surface,precision lapping using an electronic lapping guide, and one or moreannealing steps to heat the material of the slider 202 in order toproduce desired properties.

After the slider is lapped, then the edge of the slider 202 is blendedat step 306. Blending the edge of the slider 202 involves abradingmaterial from the slider 202 to produce the curved edge. For example,the slider 202 can be pressed against an abrasive surface that movesback and forth against the slider 202. In some embodiments, the abrasivesurface can be vibrated at a selected frequency to abrade the slider202. The abrasive surface can be placed at an angle to the leading face210 and the primary plane of the slider 202. In particular embodiments,the angle between a plane of the abrasive surface and the primary planeof the slider 202 is between 10 and 20 degrees. The abrasive surface canalso be placed over a compliant material, such as a rubber pad, so thatthe abrasive surface wraps around the slider 202, which can produce amore uniform blended edge. In particular embodiments, the compliantmaterial may be a rubber pad with a Shore durometer hardness of at least40 Shore D. Both the leading and trailing edges of the slider 202 may beblended.

After the edge blending step 306, the slider may be cleaned at step 308to remove stray particles. The carbon overcoat is formed at step 310.Following the carbon overcoat deposition, an air bearing surface 206including at least step feature conformal to the leading edge blend isformed at step 312. The conformal step feature 218 may be formed usingany combination of masking, etching, milling, or other processes forrecessing surfaces in the air bearing surface of the slider 202. Theconformal step feature 218 may include any kind of step, channel, dam,or the like used in air bearing surfaces of sliders. The formation ofthe conformal step feature 218 is the last step of the method 300 ofFIG. 4, but it should be understood that the described method may beintegrated with any number of compatible slider formation processes, andthat the described steps do not all necessarily need to be performed orperformed in the described order in order to practice methods accordingto the present invention.

More generally, in the foregoing specification, the invention isdescribed with reference to specific exemplary embodiments thereof, butthose skilled in the art will recognize that the invention is notlimited thereto. It is contemplated that various features and aspects ofthe above-described invention may be used individually or jointly andpossibly in an environment or application beyond those described herein.The specification and drawings are, accordingly, to be regarded asillustrative and exemplary rather than restrictive. The terms“comprising,” “including,” and “having,” as used herein are intended tobe read as open-ended terms.

1. A method of forming a slider, comprising: forming a leading edgeblend on a leading edge of the slider; and after the leading edge blendis formed, forming at least one step feature conformal to the leadingedge blend, wherein the step feature is formed by etching the leadingedge blend.
 2. The method of claim 1 further comprising forming a carbonovercoat on the slider after the leading edge blend is formed.
 3. Themethod of claim 1, wherein the step of forming the leading edge blendcomprising abrading the slider with an abrasive surface.
 4. The methodof claim 3, wherein the abrasive surface is placed at an angle to theair bearing surface while abrading the slider.
 5. The method of claim 4,wherein the angle is between 10 and 20 degrees.
 6. The method of claim3, wherein a compliant material is placed behind the abrasive surfaceduring the abrading of the slider.
 7. The method of claim 6, wherein thecompliant material has a durometer hardness greater than 40 Shore D. 8.The method of claim 3, further comprising vibrating the abrasivesurface.
 9. The method of claim 1, further comprising forming a trailingedge blend on a trailing edge of the slider.
 10. The method of claim 1,further comprising forming a blend on at least one side of the slider.